I work with multiple computers around the shop. Moving from one to the other as needed. When sitting at one screen, I can have other screens within my field of vision. The screens will go to a blank, black screen saver mode after a time.
While working at one screen. I sometimes notice another screen go black at the far edge of my visual field. The odd thing is, I was not consciously noticing that screen, until it went black. But, when it goes black, I see that lit screen, go to black. To be precise, I do not suddenly notice a black space, where a bright space was. I actually see a bright screen go black. Going black caught my attention. So how do I see it bright, before it goes black?
It seems as if my visual system is going back an instant, to show me the situation a moment before the change occurred.
As if there is an automatic short term instant replay system. Always storing a certain amount of visual info, in case you need a quick playback to figure out what happened. But it seems real and right now.
I wonder if it is real. An actual separate part of the visual system. Or if it is other parts of the brain, making up the story based on the situation and feeding it to you as real visual information?
This. There is a huge amount of pre-conscious processing that happens in the visual system.
We tend to think of our senses piping information to our brains, but that’s not really accurate. Our moment-to-moment sensory experience is a simulation constructed by our brains to account for the sense data we’re receiving: “There’s some red cones firing at this point on my retina, so I’ll add a red ball to the scene!”
How our brains fill in the scene is a product of our expectations as much as our senses. We’ll see what we think we should see, and if we see something that we think we shouldn’t see, it takes a while for the simulation to catch up.
In the case of your example, an abrupt change of brightness in your visual field causes your brain to construct an explanation for why it happened. So your conscious mind sees the screen turn off.
Generally the estimates I see for consciousness to register an event are in the .4 to .5 second range. Some researchers have claimed numbers as high as a couple seconds (!). Note that is from stimulus to consciousness. Your subconscious brain reacts in far shorter time. Hence your consciousness notes your reaction after you already have reacted. I think this might apply better to the OP’s question. I.e., the subconscious brains notes the change, tells the conscious brain to pay attention to the screen off to the side and that signal arrives before the “video” finally arrives.
Your consciousness thinks it’s king of the brain, but it actually is mostly just enjoying the show.